Whether you’re out in the wilderness or hooked to an untrusted water supply, you don’t need to count on expensive and wasteful plastic purifiers to filter the water you drink. Here are six simple ways you can purify your own water: at home, on vacation, or during your next camping adventure. All you’ll need to complete each of these is a fire source, the sun, and a few items you can find in just about any backyard.
Solar water disinfection (called SODIS) is a process by which the sun disinfects water with just two ingredients: a clear plastic bottle and contaminated water. Simply fill a plastic bottle with the contaminated water, and sit it out in the sun for at least one full day. UV rays from the sun will kill just about any viruses and bacteria—although this method does not protect against chemical contamination.
There are a few more things you should know about SODIS before assuming you have a handle on this method. For one, it's useless if it is raining out (although in that case, you could just be collecting the rainwater). The bottle should not be glass for this to work properly, and you can't use anything bigger than a 2-liter plastic bottle.
If you find yourself in a situation without a trustworthy water source, boiling is an easy option that will get rid of most disease-causing microorganisms such as pathogenic bacteria, protozoa and viruses. One word of caution: boiling will not remove salts, heavy metals, or other chemicals. It also won’t help at all with dirt or other solid materials.
You can build a fire in the woods, use your stove top, or any other strong heat source to get your water boiling. To properly kill off disease, you need to keep the water at a rolling boil for at least one minute. If you’re in an altitude higher than 5,000 feet, extend the rolling boil to three minutes. Then, let the water cool naturally and store it in clean vessels with lids. Boiled water doesn’t taste great, but you can mitigate the flatness of the water with a pinch of salt for every liter of water you boil. Pouring the water back and forth between clean containers a few times will also help with the taste.
Solar stills, in use since the 16th century, and recreate the natural water-purification system of evaporation and rainfall. The resulting distilled water doesn’t acquire the flat taste of boiled water, and is free of salts, microorganisms and pathogens. You can even use a solar still to turn ocean water into drinking water.The only caveat is that in order to make a solar still, you need a lot of sun, a cup or jar, bowl, and plastic wrap. Food for thought when you’re packing for your next expedition.
To make a solar still, you need a large bowl or similarly shaped pot with a wide, flat bottom. Into the center of the vessel goes a cup, glass or jar that is not taller than your large bowl and has some weight to it so it will not float when you fill the surrounding container with water.
Fill the bowl with the water in need of purification. You don’t want any of the water to get into the cup standing in the center. Then, cover everything with plastic wrap and put a weight over center of the plastic so the weight is sitting over your cup or glass. You don’t want the weight and glass to touch, but you do want the weight to create a slight dip in the plastic.
Put the whole thing out in the sun, and wait. Eventually the sun will cause the water to evaporate, and the plastic will trap the evaporated water along the bottom of the plastic stretched over top of the bowl. Your center weight will pull those water droplets along the plastic until they eventually drop into the cup, purified.
Another way to get purified water is to procure it yourself... from plants.
During transpiration, water that was absorbed in the ground by plant roots travels through the trunk and stems of a plant before being released from the plant's leaves and evaporated into the air. This water vapor can be easily trapped by a survivalist for clean, purified water. Just don't try this on poisonous plants! Simply place a large, clear garbage bag over a cluster of branches on a leafy shrub or tree and tie the bag off. Leave it sitting in the sun for a full day. The water droplets will gather at the lowest point of the bag, and can yield up to a half cup of water every day.
Charcoal, gravel, rocks, sand, and even grass make great water filters for bacteria and chemicals. But be forewarned: These systems are not thorough. Only use this sort of filter to create drinking water if you are in an emergency situation. Otherwise, use this filter in tandem with another purifying source.
To make the filter, simply make holes with a drill or hammer and nail in the bottom of a large bucket. If you're outside with no buckets lying around, you can cut a bottle in half and use that, or use thin bark or even leaves to make funnels that you then set into a vessel like a cup, bowl, or rock with a deep depression in it. Then, layer your materials. Start with pebbles, followed by sand, a piece of cloth (bandages will also work), charcoal (from your campfire), another piece of cloth or bandage, more sand, and more pebbles. Place a catchment bin under the bucket, and then pour the water to filter over the top of the sand. When all the water has made it through the filter and into the bottom catchment, repeat the filtration at least two or three more times.
If you don't have power or fire for boiling, bleach can work very efficiently to disinfect your water. Always remember to get rid of debris in the water first. You can either let it all settle at the bottom of the holding vessel (this usually takes about 30 minutes), or you can strain it with a cloth or screen.
How much bleach you need will depend on how bad the water is. Cold and/or dirty water requires four drops of bleach per quart, while warm and/or clear water only needs two. Once you've added the appropriate amount of drops, put a lid on your container and shake it for 60 seconds. Flip the bottle upside down and unscrew the lid just enough for a little bit of water to seep out, thereby disinfecting the cap and bottle threads. Then screw the lid back on, wipe the exterior of the bottle and lid down, and let it sit in a dark or shady spot for 30 minutes before opening the lid again. If you take the lid off and can't smell chlorine, add another two drops and wait for another half hour before drinking.